Opti-Spark
- Thread starter kingman
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vettepilot
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What it does is raise your blood pressure when it craps out, and it costs more than a visit to your cardiologist.
Sorry about that, but I wanted to prep you for what's coming. The opti-spark is actually your ignition module and distributor all rolled into one unit. It looks good on paper, it is driven directly off the front of the camshaft and the ignition is triggered by a disk that has 360 slots that interupt a light beam for sensing ignition timing. The problem lies in it's closest neighbor, the waterpump. The waterpump is driven by a short splined shaft that comes out the front of the engine about two inches above the top of the opti-spark unit. The seal that retains the coolant around that waterpump drive shaft has a habit of failing, and the coolant naturally falls onto the top radius of the opti-spark unit, that is supposed to be sealed... but through heat and vibration that seal usually cures and shrinks thus failing after about 20 - 40,000 miles. Just about the time the waterpump input shaft begins to seep through the weep hole under the shaft.
So the first indication you will probably have that you need a waterpump, will be when the engine either doesn't start, sounds like it is cross firing, or suddenly begins to stumble under a load such as hard acceleration.
Prices vary greatly, depending on where you purchase your parts, and if you can do the work yourself. I highly recommend going with genuine GM parts on this, not just to keep the Corvette genuine GM, but to get the GM parts warranty. Depending on how many miles you put on your Vette per year, you might find yourself getting pretty good at removing the serpentine belt, the waterpump, the harmonic balancer, and the opti-spark during the lifetime of your car.
I had over 145,000 miles on mine when I traded it in, I did the job three times. The first time at 75,000 miles to replace the leaking waterpump, the second time about a month later to replace the opti-spark that was ruined by the aforementioned leaking waterpump, and the third time to replace both again at 110,000 miles. After the first "trial run" counting the gasket scraping, I could get it all apart and back together again in about 1 1/2 hours. Well, that's the opti-spark story, except for your second question. Yes the opti-spark was modified in 95 to have a vacuum assisted breather pipe installed to help purge the moisture, and thus reduce the failure incidence of the opti-spark. I'm not sure if it actually did reduce the number of failures or not.
vettepilot
Sorry about that, but I wanted to prep you for what's coming. The opti-spark is actually your ignition module and distributor all rolled into one unit. It looks good on paper, it is driven directly off the front of the camshaft and the ignition is triggered by a disk that has 360 slots that interupt a light beam for sensing ignition timing. The problem lies in it's closest neighbor, the waterpump. The waterpump is driven by a short splined shaft that comes out the front of the engine about two inches above the top of the opti-spark unit. The seal that retains the coolant around that waterpump drive shaft has a habit of failing, and the coolant naturally falls onto the top radius of the opti-spark unit, that is supposed to be sealed... but through heat and vibration that seal usually cures and shrinks thus failing after about 20 - 40,000 miles. Just about the time the waterpump input shaft begins to seep through the weep hole under the shaft.
So the first indication you will probably have that you need a waterpump, will be when the engine either doesn't start, sounds like it is cross firing, or suddenly begins to stumble under a load such as hard acceleration.
Prices vary greatly, depending on where you purchase your parts, and if you can do the work yourself. I highly recommend going with genuine GM parts on this, not just to keep the Corvette genuine GM, but to get the GM parts warranty. Depending on how many miles you put on your Vette per year, you might find yourself getting pretty good at removing the serpentine belt, the waterpump, the harmonic balancer, and the opti-spark during the lifetime of your car.
I had over 145,000 miles on mine when I traded it in, I did the job three times. The first time at 75,000 miles to replace the leaking waterpump, the second time about a month later to replace the opti-spark that was ruined by the aforementioned leaking waterpump, and the third time to replace both again at 110,000 miles. After the first "trial run" counting the gasket scraping, I could get it all apart and back together again in about 1 1/2 hours. Well, that's the opti-spark story, except for your second question. Yes the opti-spark was modified in 95 to have a vacuum assisted breather pipe installed to help purge the moisture, and thus reduce the failure incidence of the opti-spark. I'm not sure if it actually did reduce the number of failures or not.
vettepilot
- Thread starter
- #3
kingman
Well-known member
Thanks for the feedback.
So, right now l'm back to the 95-96 model years.
Its so tough finding a good vette at an affordable price. When a vette is traded in and wholesaled out it's only worth (95-96 coupe) 13-15 thou tops no matter what condition and if the mileage is under 70,000miles.
When the C6 comes out the late C4's will drop in price, and then begin their rebound.
So, right now l'm back to the 95-96 model years.
Its so tough finding a good vette at an affordable price. When a vette is traded in and wholesaled out it's only worth (95-96 coupe) 13-15 thou tops no matter what condition and if the mileage is under 70,000miles.
When the C6 comes out the late C4's will drop in price, and then begin their rebound.
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